
 ;
 ;                       Find    n C r       
 ;                        ( L I S P )        
 ;


 ( define nCr
   ( lambda ( n r )
     ( begin
       ( if ( or ( = r 0 ) ( = r n ) )
           1
         ( begin
           ( if ( or ( = r 1 ) ( = r ( - n 1 ) ) )
               n
             ( begin
               ( / ( FACT  n ) ( * ( FACT  r ) ( FACT ( - n r ) ) ) )
              )
            )
          )
        )
      )
    )
  )

 ( define FACT
   ( lambda ( number )
     ( if ( zero? number )
         1
       ( * number ( FACT ( - number 1 ) ) )
      )
    )
  )
